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Location and Dates of Repeat Sampling Trips
| Location | Initial Sampling Trip Date |
Second Sampling Trip Date |
|---|---|---|
| Columbus, Ohio | March 2004 | April 2006 |
| Milwaukee, Wis. | April 2004 | May 2006 |
| Phoenix, Ariz. | June 2004 | June 2006 |
| Portland, Ore. | July 2004 | July 2006 |
| Denver, Colo. | August 2004 | August 2006 |
| Philadelphia, Pa. | March 2005 | March 2006 |
